Greek historian and rhetorician, born at Chios about 380 BC. In early youth he seems to have spent some time at Athens, along with his father, who had been exiled on accouut of his Laconian sympathies. Here he became a pupil of Isocrates, and rapidly made great progress in rhetoric; we are told that Isocrates used to say that Ephorus required the spur but Theopompus the bit. At first he appears to have composed epideictic speeches, in which he attained to such proficiency that in 352-351 he gained the prize of oratory given by Artemisia in honor of her husband, although Isocrates was himself among the competitors. It is said to have been the advice of his teacher that finally determined his career as an historian -- a career for which he was peculiarly qualified owing to his abundant patrimony and his wide knowledge of men and places. Through the influence of Alexander the Great, he was restored to Chios about 333, and figured for some time as one of the leaders of the aristocratic party in his native town. After Alexander's death he was again expelled, and took refuge with Ptolemy in Egypt, where he appears to have met with a somewhat cold reception. The date of his death is unknown.

The works of Theopompus were chiefly historical, and are much quoted by later writers. They included an Epitome of Herodotus's History (the genuineness of which is doubted), the Hellenics, the History of Philip, and several panegyrics and hortatory addresses, the chief of which was the Letter to Alexander. The Hellenics treated of the history of Greece, in twelve books, from 411 (where Thucydides breaks off) to 394 -- the date of the battle of Cnidus. Of this work only a few fragments were known up until 1907. The papyrus fragment of a Greek historian of the 4th century BC, published in Oxyrhynchus Papyri (1908), has been recognized as a portion of the Hellenics. This identification has been disputed, some attributing the fragment to concern the events of the year 395 BC to Cratippus. A far more elaborate work was a history of Philip's reign in 58 books, with digressions on the names and customs of the various races and countries of which he had occasion to speak, which were so numerous that Philip V of Macedon reduced the bulk of the history from 58 to 16 books by cutting out those parts which had no connection with Macedonia. It was from this history that Trogus Pompeius (of whose Historiae Philippicae we possess the epitome by Justin) derived much of his material. Fifty-three books were extant in the time of Photius (9th century), who read them, and has left us an epitome of the 12th book. Several fragments, chiefly anecdotes and strictures of various kinds upon the character of nations and individuals, are preserved by Athenaeus, Plutarch and others.

Of the Letter to Alexander we possess one or two fragments cited by Athenaeus, animadverting severely upon the immorality and dissipations of Harpalus. The Attack upon Plato, and the treatise On Piety, which are sometimes referred to as separate works, were perhaps only two of the many digressions in the history of Philip; some writers have doubted their authenticity.

The libellous attack on the three cities -- Athens, Sparta and Thebes -- was published under the name of Theopompus by his enemy Anaximenes of Lampsacus. The nature of the extant fragments fully bears out the divergent criticisms of antiquity upon Theopompus. Their style is clear and pure, full of choice and pointed expressions, but lacking in weight and dignity. The artistic unity of his work suffered severely from the frequent and lengthy digressions already referred to. The most important was that On the Athenian Demagogues in the 10th book of the Philippica, containing a bitter attack on many of the chief Athenian statesmen, and generally recognized as having been freely used by Plutarch in several of the Lives. Another fault of Theopompus was his excessive fondness for romantic and incredible stories; a collection of some of these was afterwards made and published under his name. He was also severely blamed in antiquity for his censoriousness, and throughout his fragments no feature is more striking than this. On the whole, however, he appears to have been fairly impartial. Philip himself he censures severely for drunkenness and immorality, while Demosthenes receives his warm praise.